The effects of some organic solvents on the absorption of digoxin by man

Ten healthy subjects took each of 6 different solutions of 0.5 mg digoxin in a study of the effect of different solvents on absorption. Bioavailability was measured by the urinary recovery of digoxin in the eight days after each dosing. The six liquid preparation were aqueous solution, an organic solvent complex (lanoxicaps fill) for which solvent assisted absorption has been suggested, digoxin elixir, and three different solutions each comprising a single organic solvent in the concentration used in lanoxicaps plus water to make up the balance. Pure aqueous solution and lanoxicaps fill had the highest bioavailability as judged by urinary recovery but there was no significant different at the 5% level between the urinary recovery from the lanoxicap fill, the elixir and the two preparations with water as the preponderant solvent. It is concluded that the greater bioavailability of digoxin from lanoxicaps than from tablet formulations is more likely to ve due at least in part to delivery of digoxin already dissolved than to the identities of the solvents. The rate of intestinal digoxin uptake may possibly influence the degree of urinary recovery.